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gdbserver: move_out_of_jump_pad_callback misses switching current thread 

While hacking on the fix for PR threads/18600 (Threads left stopped
after fork+thread spawn), I once saw its test (fork-plus-threads.exp)
FAIL against gdbserver because move_out_of_jump_pad_callback has a
gdb_breakpoint_here call, and the caller isn't making sure the current
thread points to the right thread.  In the case I saw, the current
thread pointed to the wrong process, so gdb_breakpoint_here returned
the wrong answer.  Unfortunately I didn't save logs.  Still, seems
obvious enough and it should fix a potential occasional racy FAIL.

Tested on x86_64 Fedora 20.

gdb/gdbserver/ChangeLog:
2015-08-06  Pedro Alves  <palves@redhat.com>

	* linux-low.c (move_out_of_jump_pad_callback): Temporarily switch
	the current thread.
This commit is contained in:
Pedro Alves 2015-07-23 16:01:01 +01:00
parent bf47e2482d
commit f0ce0d3a33
2 changed files with 12 additions and 0 deletions
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5
gdb/gdbserver/ChangeLog
View File

@ -1,3 +1,8 @@
2015-08-06 Pedro Alves <palves@redhat.com>
* linux-low.c (move_out_of_jump_pad_callback): Temporarily switch
the current thread.
2015-08-06 Pedro Alves <palves@redhat.com>
* linux-low.c (linux_write_memory): Rewrite debug output to avoid

7
gdb/gdbserver/linux-low.c
View File

@ -3664,6 +3664,7 @@ static void
move_out_of_jump_pad_callback (struct inferior_list_entry *entry)
{
struct thread_info *thread = (struct thread_info *) entry;
struct thread_info *saved_thread;
struct lwp_info *lwp = get_thread_lwp (thread);
int *wstat;
@ -3675,6 +3676,10 @@ move_out_of_jump_pad_callback (struct inferior_list_entry *entry)
}
gdb_assert (lwp->stopped);
/* For gdb_breakpoint_here. */
saved_thread = current_thread;
current_thread = thread;
wstat = lwp->status_pending_p ? &lwp->status_pending : NULL;
/* Allow debugging the jump pad, gdb_collect, etc. */
@ -3702,6 +3707,8 @@ move_out_of_jump_pad_callback (struct inferior_list_entry *entry)
}
else
lwp_suspended_inc (lwp);
current_thread = saved_thread;
}
static int